Device for equalizing the tension in a filament



Oct. 18, 1966 J. c. MARTIN 3,279,670

DEVICE FOR EQUALIZING THE TENSION IN A FILAMENT Filed Feb. 4, 1965lnvenlur A Home United States Patent 3,279,670 DEVICE FOR EQUALIZING THETENSION IN A FILAMENT Jean Claude Martin, Lyon, France, assignor toSociete Rhodiaceta, Paris, France, a French body corporate Filed Feb. 4,1965, Ser. No. 430,364 Claims priority, application France, Feb. 12,1964, 963,519 6 Claims. (Cl. 226-195) This invention relates to a devicefor equalizing the tension in travelling yarn, for example duringwin-ding.

Fluctuations of the tension in a yarn during winding result inirregularities in the product obtained, and many devices are known forequalizing this tension.

For example, there may be employed a supply cylinder rotating at aperipheral velocity higher than the winding speed of the yarn and aboutwhich the latter passes. The cylinder thus tends to drive the yarncontinuously and to supply it to the winding members almost withouttension. This device has the disadvantage that it possesses no means ofadjustment.

In another device, the yarn passes round a portion of the periphery of aroller driven at a peripheral velocity higher than the speed at whichthe yarn is travelling, and a current of air is provided to lift theyarn from the roller. The force exerted by the current of air on theyarn tends to reduce the arc embraced by the yarn on the roller, whileincrease of the tension in the yarn as it leaves the device tends toincrease the arc embraced. The change in the length of the arc embracedproduces a change in the frictional forces between the yarn and theroller, which results in a regularisation of the tension in the filamentas it leaves the device. This device operates perfectly only with lowyarn tensions.

It is an object of the present invention to provide a device forautomatically equalizing the tension in a moving yarn, regardless of thevariations of tension which occur upstream or downstream of the device.

According to the invention a device for automatically equalizing thetension in a travelling yarn comprises a cylinder adapted to be rotatedat a peripheral speed greater than the rate of travel of the yarn and inthe same direction, yarn guide means positioned to cause the yarn totravel through at least one arc in contact with the surface of thecylinder and including at least one movable yarn guide mounted so as tobe moved by an increase in the tension of the yarn in a direction whichincreases the length of at least one are over which the yarn makescontact with the cylinder, and return means tending to move the saidmovable guide in a direction which decreases the length of the said arc.

Preferably, the device comprises two movable yarn guides.

In a preferred embodiment of the/invention the movable yarn guide orguides are each mounted at or towards the end of a bar pivoted about apoint between its two ends, and the return means operate on each bar onthe other side of the pivot. Advantageously the return means comprises aspring. For example when there are two yarn guides carried on pivotedbars, the return means may comprise a single spring acting on both bars,e.g., a tensioned spring joining the two bars. It may be convenient touse curved bars one on either side of the rotating cylinder, thecurvature being suflicient to keep them out of contact with thecylinder. The surface of the guide with which the yarns make contactwill usually be such as to reduce friction to a minimum; thus it may beprovided by a freely running pulley.

The invention is illustrated in the accompanying drawing, in which,

ice

FIGURE 1 is a diagrammatical lateral view illustrating one form of yarntension equalizing device, and

FIGURE 2 is a similar view illustrating another form of such device.

, The device of FIGURE 1 comprises a cylinder 1 which is rotated at aperipheral velocity higher than the speed of travel of the yarn, twoyarn guides 2 and 2 each comprising a freely running pulley mounted atthe end of a curved bar 3, 3, the bar 3 being adapted to pivot about apoint 4 and the bar 3' about a point 4'. The other ends of the said bars(i.e., the ends remote from the yarn guides 2 and 2) are connected by aspring 5 working in tension. Alternatively, there may be employed twoindependent return springs, one for each bar. The path of the yarn isindicated at 6.

The device of FIGURE 2 comprises, in addition to the same elements asthat of FIGURE 1, two fixed y-arn guides 7 and 7'. The path of the yarndiliers from that of FIG- UR-E 1 and is illustrated at 6'. Y

In both devices, when an increase of the tension in the yarn occurs, theyarn guides 2 and 2' move towards one another, so that the arc embracedby the yarn on the cylinder 1 is increased. Since the cylinder 1 rotatesat a peripheral velocity higher than the linear speed of the yarn, asthe arc of contact is increased so is the driving force exerted by thecylinder on the yarn and the tension in the yarn is thus reduced.

When the tension in the yarn falls, the yarn guides 2 and 2' move awayfrom one another under the action of the spring 5; the arc embraced bythe yarn on the cylinder is reduced, and with it the force with whichthe yarn i driven by the cylinder, so that the tension in the yarn isincreased.

The device of the invention is thus self-adjusting, and makes itpossible to maintain a uniform tension in the travelling yarn. The valueof this tension may be ad justed in various Ways, notably by varying thereturn force of the spring 5, an increase of which produces an increasein the tension, or by varying the surface state of the cylinder 1 or bychanging the material of which it is made, whereby the coefficient offriction between the yarns and the cylinder, and consequently thetension in the yarn for a given ratio of a cylinder speed to yarn speed,is changed.

The spring working in tension may be replaced by any other equivalentsystem, e.g., by a spring working in flexure, in torsion or incompression,.a counter-weight, a pneumatic jack, or a magnetic orelectromagnetic device of the plunger type or the repulsion type.

I claim:

1. A device for automatically equalizing the tension in a travellingyarn, comprising a cylinder adapted to be rotated at a peripheral speedgreater than the rate of travel of the yarn and in the same direction,yarn guide mean positioned to cause the yarn to travel through at leastone are in contact with the surface of the cylinder and including atleast one movable yarn guide mounted so as to be moved by an increase inthe tension of the yarn in a direction which increases the length of atleast one arc over which the yarn makes contact with the cylinder, andreturn means tending to move the said movable guide in a direction whichdecreases the length of the said arc.

2. A device according to claim 1, comprising two such movable yarnguides.

3. A device according to claim 1, wherein each movable yarn guide ismounted on a bar pivoted at a point between its two ends, and the returnmeans operates on the bar the other side of the pivot.

4. A device according to claim 3, comprising two yarn guides and atension spring joining the two bars as the return means.

5. A device according to claim 1, wherein each yarn guide comprises afreely rotatable pulley adapted to make contact with the travellingyarn.

6. A device for automatically equalizing the tension in a travellingyarn, comprising a cylinder adapted to be rotated at a peripheral speedgreater than the rate of travel of the yarn and in the same direction,yarn guide means positioned to cause the yarn to travel through at leastone are in contact with the surface of the cylinder and including twomovableyarn guides, each comprising a freely rotatable pulley mounted atone end of a bar pivoted at a point between its two ends, the said barsbeing joined beyond the said pivots by a tension spring, the arrangementbeing such that in operation the yarn between the movable yarn guidestraverses at least one are on the cylinder, and that an increase in thetension in the yarn causes the movable yarn guides to move towards eachother and so increase the distance over which the yarn make contact withthe cylinder.

References Cited by the Examiner UNITED STATES PATENTS 1,752,604 4/1930Massingham 24247.l2 X 2,854,197 9/1958 MacNcil 242-5512 3,114,51212/1963 Peshel et a1 242-75.3 X

FOREIGN PATENTS 135,615 3/1952 Sweden.

M. HENSON WOOD, JR., Primary Examiner.

I. N. ERLICH, Assistant Examiner.

1. A DEVICE FOR AUTOMATICALLY EQUALIZING THE TENSION IN A TRAVELLINGYARN, COMPRISING A CYLINDER ADAPTED TO BE ROTATED AT A PERIPHERAL SPEEDGREATER THAN THE RATE OF TRAVEL OF THE YARN AND IN THE SAME DIRECTION,YARN GUIDE MEANS POSITIONED TO CAUSE THE YARN TO TRAVEL THROUGH AT LEASTONE ARC IN CONTACT WITH THE SURFACE OF THE CYLINDER AND INCLUDING ATLEAST ONE MOVABLE YARN GUIDE MOUNTED SO AS TO BE MOVED BY AN INCREASE INTHE TENSION OF THE YARN IN A DIRECTION WHICH INCREASES THE LENGTH OF ATLEAST ONE ARC OVER WHICH THE YARN MAKES CONTACT WITH THE CYLINDER, ANDRETURN MEANS TENDING TO MOVE THE SAID MOVABLE GUIDE IN A DIRECTION WHICHDECREASES THE LENGTH OF THE SAID ARC.